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I am looking for an off the shelf component for a project I am currently working on. Due to the nature of the project I cannot go into much detail about the project itself, only give a high level overview of the requirements of the desired component. I am not an electronic engineer, I am from the dark side of software engineering, so please forgive me if any of my terminology is wrong, I find myself thrown in at the deep end of this project.

I am looking for a component which can sit on the frame of a door (with part on the door itself (very similar to a burglar alarm sensor in the UK)). When the circuit is broken, the component should be able to perform a HTTP GET/POST to a URL (probably located on the local network - but not necessarily).

To this end, my component requirements are as follows:

  1. Wireless equipped (not to fussy on standards as this point, as long as major encryption formats are supported).
  2. Ability to GET/POST to a url in event of a break in the circuit.
  3. Low power consumption.
  4. Configurable
  5. Ability to exchange the power source (swap batteries)

The component should provide a SDK (at this point in time, the language used to call the SDK is not important) which can configure the device (for example, setup network configurations, give the device a unique identifier (as multiple could be used on the same network)). I do not know enough about the range of components avaiable which fit my requirements to specify how configuration should take place, but in my head I imagine it being hard-wired to a computer to perform the configuration.

Are there any such components available which would fit my requirements?

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  • \$\begingroup\$ After writing this, my initial thought is that this component is simply a wish list in my head, and such a component would not be available for purchase off the self, and if that is the answer I get, then this is fine, it gives me the justification I need to go back to the money-men on the project and inform them that they need to source someone whom can build a custom component to fit all of the requirements. \$\endgroup\$ – Mick Walker Mar 31 '13 at 20:05
  • \$\begingroup\$ This is pretty much exactly AlertMe's product: alertme.com - they sold it as a home security system, which wasn't particularly commercially successful. \$\endgroup\$ – pjc50 Mar 31 '13 at 20:35
  • \$\begingroup\$ Would a small, dedicated, battery powered RF transmitter do the job? It would communicate one-way to a receiver and this receiver would offer the extended funtionality you require. The small transmitter would just do the job of detection of "something" and impart this knowledge to the more sophisticated AC powered receiver. \$\endgroup\$ – Andy aka Mar 31 '13 at 20:43
  • \$\begingroup\$ Pjc50 the project actually has nothing to do with security. The above text was the best example I could come up with, without breaking multiple NDA's \$\endgroup\$ – Mick Walker Apr 1 '13 at 3:48
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A Raspberry Pi may be a reasonable compromise:

  • it can run various flavors of Linux, which supports TCP/IP and many flavours of security
  • it has numerous GPIO lines which can be polled by something as simple as a Python script
  • it supports many off-the-shelf USB-to-WiFi adapters
  • it consumes around 5W at peak loading, and could run for a long time off a household UPS with a switching wall-wart adapter powering it
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If you can't find it off the shelf, investigate a arduino, a wi-fi shield, some door switchs of the home-security type, a battery, and your API is the relevant arduino libraries. It's basically C with a set of high-level libraries that make it pretty easy to deal with all the hardware.

If that doesn't work for you, then I'd say you need to investigate what the DIY home security companies have to offer. I can't imagine they wouldn't have something that can do this, but I'm not sure it would be cost effective (depends on how cost sensitive you are).

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  • \$\begingroup\$ One potential issue with an Arduino is security. If secure wireless is secure enough, then no problem. If SSL is necessary also, then AAIK there isn't any accepted implementation Arduino. \$\endgroup\$ – angelatlarge Mar 31 '13 at 21:48
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Ninjablocks

Have a look at Ninjablocks: http://www.ninjablocks.com

The have a wireless button, door sensor, temp/humidity sensor among other things, e.g. http://ninjablocks.com/products/contact-sensor

The blocks run off a beagle bone circuit with an Arduino daughterboard, and the whole thing is open source. From what I can tell, the device communicates data and events back to the ninjablocks server, which you can hook into using their REST API or with their own interface:

http://docs.ninja.is/rest/rule.html

Since everything is open source, it would be easy to start with this system which you know will work, then move onto implementing your own. The code for the beagle bone could be modified to send POST messages to your own server rather than the ninjablocks one.

This system meets requirements 1,2,3 and 5. As for 4, my idea of low power is running off 2 AAs for 6 months. The door sensor might do this, but I thing the ninjablock itself requires a wall wart.

Alternative

The other thing you might think about is an Arduino with a GPRS shield and door sensor. The door sensor could wake the Arduino up from power-down sleep mode, from which it can send a POST message to your server via GPRS. The benefit being no WiFi network is necessary. However, without some experience in embedded systems I think this would take a month or more of tinkering to get something working well. A good base Arduino board would be something like a Seeeduino stalker or a Rocket Scream mini 8MHz which have been designed for low power.

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    \$\begingroup\$ Looks promising but what part of the receiver can do the "HTTP GET/POST to a URL" thing. The link didn't give any technical details that were of interest - do you have a better link? \$\endgroup\$ – Andy aka Mar 31 '13 at 22:46
  • \$\begingroup\$ I think there is a separate "server" pice here \$\endgroup\$ – angelatlarge Apr 1 '13 at 5:17

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